U.S. patent application number 16/090642 was filed with the patent office on 2019-04-18 for work implement of hydraulic excavator and method of manufacturing work implement of hydraulic excavator.
This patent application is currently assigned to KOMATSU LTD.. The applicant listed for this patent is KOMATSU LTD.. Invention is credited to Tsuyoshi ASADA, Naohiro KUNISAWA, Yuki NAKATANI, Nobuyasu SUGIHARA, Masashi UENO, Shinpei UTOU.
Application Number | 20190112779 16/090642 |
Document ID | / |
Family ID | 60786245 |
Filed Date | 2019-04-18 |
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United States Patent
Application |
20190112779 |
Kind Code |
A1 |
UTOU; Shinpei ; et
al. |
April 18, 2019 |
WORK IMPLEMENT OF HYDRAULIC EXCAVATOR AND METHOD OF MANUFACTURING
WORK IMPLEMENT OF HYDRAULIC EXCAVATOR
Abstract
The number of steps required for a welding operation of a work
implement of a hydraulic excavator is reduced while the welding
quality is improved. A boom includes a top plate, a left side plate
joined to the top plate, and a boom foot bracket. The boom foot
bracket includes an extending portion. The extending portion
includes a portion that faces a side surface of the top plate.
Inventors: |
UTOU; Shinpei; (Minato-ku,
Tokyo, JP) ; ASADA; Tsuyoshi; (Minato-ku, Tokyo,
JP) ; SUGIHARA; Nobuyasu; (Minato-ku, Tokyo, JP)
; KUNISAWA; Naohiro; (Minato-ku, Tokyo, JP) ;
NAKATANI; Yuki; (Minato-ku, Tokyo, JP) ; UENO;
Masashi; (Minato-ku, Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMATSU LTD. |
Minato-ku, Tokyo |
|
JP |
|
|
Assignee: |
KOMATSU LTD.
Minato-ku, Tokyo
JP
|
Family ID: |
60786245 |
Appl. No.: |
16/090642 |
Filed: |
June 15, 2017 |
PCT Filed: |
June 15, 2017 |
PCT NO: |
PCT/JP2017/022149 |
371 Date: |
October 2, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 3/382 20130101;
E02F 3/38 20130101; E02F 9/14 20130101; E02F 3/32 20130101 |
International
Class: |
E02F 3/38 20060101
E02F003/38; E02F 9/14 20060101 E02F009/14; E02F 3/32 20060101
E02F003/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2016 |
JP |
2016-126685 |
Claims
1. A work implement of a hydraulic excavator, the work implement
comprising: a first plate material; a second plate material joined
to the first plate material; a third plate material joined to the
first plate material and facing the second plate material at a
distance from the second plate material; and a fourth plate
material joined to the second plate material and the third plate
material and facing the first plate material at a distance from the
first plate material, the first plate material, the second plate
material, the third plate material, and the fourth plate material
being joined to one another to form a box-shaped structure body,
the work implement further comprising a first attachment member
joined to each of the first plate material, the second plate
material, the third plate material, and the fourth plate material
at an end of the box-shaped structure body in a longitudinal
direction of the box-shaped structure body, the first attachment
member including an extending portion that extends in the
longitudinal direction of the box-shaped structure body, the
extending portion including a portion that faces a side surface of
the first plate material.
2. The work implement of a hydraulic excavator according to claim
1, wherein a cutout portion is provided in a portion of the first
plate material that faces the extending portion.
3. The work implement of a hydraulic excavator according to claim
2, wherein the first plate material includes a first surface that
forms an outer surface of the box-shaped structure body, and a
first back surface on an opposite side of the first surface, a
portion of the first attachment member that faces the first back
surface is provided with a groove preparation surface that forms a
groove together with the first back surface, and a portion of the
side surface that includes the cutout portion in the first plate
material and a bottom portion of the groove are continuous with
each other when seen from a direction perpendicular to the first
surface.
4. The work implement of a hydraulic excavator according to claim
2, wherein the cutout portion is formed in the longitudinal
direction of the box-shaped structure body so as to extend from an
end of the first plate material beyond a leading end of the
extending portion in the longitudinal direction.
5. The work implement of a hydraulic excavator according to claim
1, wherein the extending portion has a bank shape formed such that
a protrusion height decreases toward a leading end of the extending
portion in the longitudinal direction.
6. The work implement of a hydraulic excavator according to claim
1, wherein the first attachment member is a cast product.
7. A method of manufacturing a work implement of a hydraulic
excavator, the work implement including: a first plate material; a
second plate material joined to the first plate material; a third
plate material joined to the first plate material and facing the
second plate material at a distance from the second plate material;
and a fourth plate material joined to the second plate material and
the third plate material and facing the first plate material at a
distance from the first plate material, the first plate material,
the second plate material, the third plate material, and the fourth
plate material being joined to one another to form a box-shaped
structure body, the work implement further including a first
attachment member joined to each of the first plate material, the
second plate material, the third plate material, and the fourth
plate material at an end of the box-shaped structure body in a
longitudinal direction of the box-shaped structure body, the first
attachment member including an extending portion that extends in
the longitudinal direction of the box-shaped structure body, the
extending portion including a portion that faces a side surface of
the first plate material, the method comprising: forming a recess
portion as a partial recess in a surface of the first attachment
member, the recess portion being located between the extending
portion and the side surface of the first plate material that faces
the extending portion; and filling up the recess portion by
welding.
Description
TECHNICAL FIELD
[0001] The present invention relates to a work implement of a
hydraulic excavator and a method of manufacturing the work
implement of the hydraulic excavator.
BACKGROUND ART
[0002] Conventionally, regarding a work implement of a hydraulic
excavator, there has been a proposed technique by which welding is
performed along a line formed between a dam and the abutting
surface of a plate material divided along the border with the dam
to thereby form a weld bead along the line (for example, see
Japanese Patent Laying-Open No. 2015-151741 (PTD 1)).
CITATION LIST
Patent Literature
PTL 1: Japanese Patent Laying-Open No. 2015-151741
SUMMARY OF INVENTION
Technical Problem
[0003] When each of members constituting a work implement of a
hydraulic excavator is joined by welding, it is desirable to form a
continuous weld line for the purpose of reducing the number of
steps required for the welding operation and for improving the
welding quality.
[0004] An object of the present invention is to provide a work
implement of a hydraulic excavator, for which the number of steps
required for a welding operation can be reduced and also the
welding quality can be improved.
Solution to Problem
[0005] A work implement of a hydraulic excavator according to the
present invention includes: a first plate material; a second plate
material joined to the first plate material; a third plate material
joined to the first plate material and facing the second plate
material at a distance from the second plate material; and a fourth
plate material joined to the second plate material and the third
plate material and facing the first plate material at a distance
from the first plate material. The first plate material, the second
plate material, the third plate material, and the fourth plate
material are joined to one another to form a box-shaped structure
body. The work implement of the hydraulic excavator further
includes a first attachment member joined to each of the first
plate material, the second plate material, the third plate
material, and the fourth plate material at an end of the box-shaped
structure body in a longitudinal direction of the box-shaped
structure body. The first attachment member includes an extending
portion that extends in the longitudinal direction of the
box-shaped structure body. The extending portion includes a portion
that faces a side surface of the first plate material.
[0006] A manufacturing method according to the present invention is
a method of manufacturing a work implement of a hydraulic
excavator. The work implement of the hydraulic excavator includes:
a first plate material; a second plate material joined to the first
plate material; a third plate material joined to the first plate
material and facing the second plate material at a distance from
the second plate material; and a fourth plate material joined to
the second plate material and the third plate material and facing
the first plate material at a distance from the first plate
material. The first plate material, the second plate material, the
third plate material, and the fourth plate material are joined to
one another to form a box-shaped structure body. The work implement
of the hydraulic excavator further includes a first attachment
member joined to each of the first plate material, the second plate
material, the third plate material, and the fourth plate material
at an end of the box-shaped structure body in a longitudinal
direction of the box-shaped structure body. The first attachment
member includes an extending portion that extends in the
longitudinal direction of the box-shaped structure body. The
extending portion includes a portion that faces a side surface of
the first plate material. The manufacturing method includes:
forming a recess portion as a partial recess in a surface of the
first attachment member, the recess portion being located between
the extending portion and the side surface of the first plate
material that faces the extending portion; and filling up the
recess portion by welding.
Advantageous Effects of Invention
[0007] According to the present invention, the number of steps
required for the welding operation of the work implement of the
hydraulic excavator can be reduced while the welding quality can be
improved.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a diagram illustrating the external appearance of
a hydraulic excavator according to an embodiment.
[0009] FIG. 2 is a side view showing the schematic configuration of
a boom shown in FIG. 1.
[0010] FIG. 3 is a cross-sectional view of the boom taken along a
line III-III shown in FIG. 2.
[0011] FIG. 4 is an enlarged perspective view of a region IV in
FIG. 2.
[0012] FIG. 5 is an enlarged perspective view showing a part of a
top plate.
[0013] FIG. 6 is a perspective view showing the configuration of a
boom foot bracket.
[0014] FIG. 7 is a plan view of region IV in FIG. 2.
[0015] FIG. 8 is a side view of region IV in FIG. 2.
[0016] FIG. 9 is a perspective view showing the state where the top
plate and the boom foot bracket are welded to each other.
[0017] FIG. 10 is a perspective view showing the state where the
top plate and the boom foot bracket are welded to each other, as
seen at a different angle.
[0018] FIG. 11 is a side view showing the schematic configuration
of an arm shown in FIG. 1.
DESCRIPTION OF EMBODIMENTS
[0019] In the following, a work implement of a hydraulic excavator
and a method of manufacturing the work implement of the hydraulic
excavator according to an embodiment will be described. In the
following description, the same components are designated by the
same reference characters. Names and functions thereof are also the
same. Accordingly, the detailed description thereof will not be
repeated.
[0020] FIG. 1 is a diagram illustrating the external appearance of
a hydraulic excavator 100 according to an embodiment.
[0021] Hydraulic excavator 100 mainly includes a traveling unit 1,
a revolving unit 3, and a work implement 4. The main body of the
hydraulic excavator is formed of traveling unit 1 and revolving
unit 3. Traveling unit 1 includes a pair of crawler belts on the
right and left sides. Revolving unit 3 is mounted in traveling unit
1 via a revolving mechanism in an upper portion of traveling unit
1. Revolving unit 3 includes an operator's cab 8.
[0022] Work implement 4 is pivotally supported on revolving unit 3
so as to be operable in the up-down direction, and configured to
perform such work as excavation of soil. Work implement 4 includes
a boom 5, an arm 6, and a bucket 7. Boom 5 has a base portion that
is coupled to revolving unit 3. Arm 6 is coupled to an end of boom
5. Bucket 7 is coupled to an end of arm 6. Each of boom 5, arm 6
and bucket 7 is driven by a hydraulic cylinder, so that work
implement 4 can be driven.
[0023] FIG. 2 is a side view showing the schematic configuration of
boom 5 shown in FIG. 1. FIG. 3 is a cross-sectional view of boom 5
taken along a line III-III shown in FIG. 2. As shown in FIGS. 2 and
3, boom 5 has a top plate 11, a left side plate 12, a right side
plate 13, and a bottom plate 14. As shown in FIG. 3, left side
plate 12 and right side plate 13 are joined at their upper ends to
top plate 11 by welding and also joined at their lower ends to
bottom plate 14 by welding. Right side plate 13 faces left side
plate 12 at a distance from left side plate 12. Left side plate 12
and right side plate 13 are disposed approximately in parallel with
each other. Bottom plate 14 faces top plate 11 at a distance from
top plate 11. Top plate 11 and bottom plate 14 are disposed
approximately in parallel with each other.
[0024] As shown in FIG. 3, top plate 11, left side plate 12, right
side plate 13, and bottom plate 14 are joined to one another to
form a box-shaped structure body 19. A weld bead 111 is formed in a
portion where top plate 11 and left side plate 12 are joined to
each other. A weld bead 112 is formed in a portion where top plate
11 and right side plate 13 are joined to each other. A weld bead
113 is formed in a portion where left side plate 12 and bottom
plate 14 are joined to each other. A weld bead 114 is formed in a
portion where right side plate 13 and bottom plate 14 are joined to
each other.
[0025] Collectively referring to FIG. 2, top plate 11, left side
plate 12, right side plate 13, and bottom plate 14 each have an
elongated plate shape. Box-shaped structure body 19 is formed as an
elongated structure body extending in the longitudinal direction of
boom 5. The longitudinal direction of box-shaped structure body 19
corresponds to the direction perpendicular to the surface of the
sheet of paper showing FIG. 3
[0026] As shown in FIG. 2, a boom foot bracket 15 is joined to one
end of box-shaped structure body 19 in its longitudinal direction.
Also, an arm attachment bracket 16 is joined to the other end of
box-shaped structure body 19 in its longitudinal direction. Boom
foot bracket 15 and arm attachment bracket 16 are joined to one end
and the other end, respectively, of box-shaped structure body 19 in
its longitudinal direction so as to be connected to each of top
plate 11, left side plate 12, right side plate 13 and bottom plate
14. Boom foot bracket 15 forms the rear end portion of boom 5 while
arm attachment bracket 16 forms the front end portion of boom 5.
Boom foot bracket 15 is coupled to revolving unit 3 via a pin. Arm
6 is coupled to arm attachment bracket 16 via a pin.
[0027] In the embodiment, the direction in which top plate 11 and
bottom plate 14 are aligned (the up-down direction in FIG. 3) is
referred to as an up-down direction. The direction in which left
side plate 12 and right side plate 13 are aligned (the right-left
direction in FIG. 3) is referred to as a right-left direction. The
direction in which boom 5 extends or the longitudinal direction of
box-shaped structure body 19 (the direction perpendicular to the
surface of the sheet of paper showing FIG. 3) is referred to as a
front-rear direction. In the front-rear direction, the side on
which boom 5 is coupled to revolving unit 3 corresponds to a rear
direction while the side on which arm 6 is coupled to boom 5
corresponds to a front direction.
[0028] A boom cylinder attachment portion 17 is provided
approximately in the center portion of each of left side plate 12
and right side plate 13 in the front-rear direction. The leading
end of the boom cylinder for driving boom 5 is coupled to boom
cylinder attachment portion 17. An arm cylinder attachment portion
18 is provided approximately in the center portion in the
front-rear direction on the upper surface side of top plate 11. The
base end of the arm cylinder for driving arm 6 is coupled to arm
cylinder attachment portion 18.
[0029] Each of top plate 11, left side plate 12, right side plate
13, and bottom plate 14 may be formed of one plate material.
Alternatively, a plurality of plate materials may be joined to one
another by welding or the like to thereby form each of top plate
11, left side plate 12, right side plate 13, and bottom plate 14. A
reinforcement member for enhancing the strength of boom 5 may be
disposed in the internal space of box-shaped structure body 19.
[0030] FIG. 4 is an enlarged perspective view of a region IV in
FIG. 2. As shown in FIG. 4, left side plate 12 is formed in a flat
plate shape. Left side plate 12 has a surface 31 that forms the
outer surface of box-shaped structure body 19 shown in FIG. 3, and
a side surface 32 that faces boom foot bracket 15. Surface 31 is
formed in a planar shape. Side surface 32 extends approximately
orthogonal to surface 31.
[0031] Top plate 11 has a surface 21, a back surface 22 on the
opposite side of surface 21, a side surface 23, and an end face 24.
FIG. 5 is an enlarged perspective view showing a part of top plate
11. In the range of the partial view of top plate 11 shown in each
of FIGS. 4 and 5, top plate 11 has a flat plate shape, and surface
21 and back surface 22 each have a planar shape. Surface 21 forms
the outer surface of box-shaped structure body 19 shown in FIG. 3.
Back surface 22 forms the inner surface of box-shaped structure
body 19 shown in FIG. 3. Side surface 23 is continuous with surface
21 and back surface 22. Side surface 23 is approximately orthogonal
to surface 21 and back surface 22.
[0032] End face 24 forms the rear end face of top plate 11. End
face 24 is formed as a tapered surface inclined with respect to the
thickness direction of top plate 11. The boundary portion between
back surface 22 and end face 24 is located more rearward in the
front-rear direction than the boundary portion between surface 21
and end face 24. End face 24 is inclined with a downward slope from
surface 21 toward back surface 22. End face 24 is continuous with
each of surface 21 and back surface 22.
[0033] Top plate 11 is provided with a cutout portion 28 obtained
by cutting out a part of side surface 23. The length of top plate
11 in the right-left direction is reduced by cutout portion 28.
Side surface 23 has cutout forming surfaces 25 and 26. Cutout
forming surfaces 25 and 26 form the wall surface of cutout portion
28. Cutout forming surfaces 25 and 26 extend in the thickness
direction of top plate 11.
[0034] Cutout forming surface 25 is formed in a planar shape
extending in the front-rear direction. Cutout forming surface 26 is
formed in a planar shape that is inclined with respect to the
front-rear direction. Cutout forming surface 25 is continuous with
end face 24. Cutout forming surface 25 is provided between end face
24 and cutout forming surface 26. Cutout forming surfaces 25 and 26
each are continuous with surface 21 and back surface 22. Cutout
forming surfaces 25 and 26 each are approximately orthogonal to
surface 21 and back surface 22.
[0035] FIG. 6 is a perspective view showing the configuration of
boom foot bracket 15. Boom foot bracket 15 is a cast product formed
by casting, for example, which is a metal cast product such as cast
steel or weldable cast iron. Boom foot bracket 15 is integrally
molded. As shown in FIG. 6, boom foot bracket 15 has a mount
surface 59 on which top plate 11 is mounted.
[0036] As shown in FIGS. 4 and 6, boom foot bracket 15 has a rear
wall portion 51. Rear wall portion 51 protrudes upward with respect
to mount surface 59. Rear wall portion 51 extends in the right-left
direction. Rear wall portion 51 has a bank shape. Rear wall portion
51 has a facing surface 52 that faces end face 24 of top plate 11.
Facing surface 52 extends along end face 24 at a distance from end
face 24. The distance between facing surface 52 and end face 24
increases gradually with increasing distance upward from mount
surface 59.
[0037] Boom foot bracket 15 has an extending portion 54. Extending
portion 54 protrudes upward with respect to mount surface 59.
Extending portion 54 extends in the front-rear direction. Extending
portion 54 extends in the longitudinal direction of box-shaped
structure body 19 shown in FIG. 3. Extending portion 54 extends
frontward from rear wall portion 51 to a leading end 55. Leading
end 55 corresponds to a leading end portion of extending portion 54
in the longitudinal direction of box-shaped structure body 19.
Extending portion 54 has a bank shape formed such that the
protrusion height decreases toward leading end 55.
[0038] Extending portion 54 and side surface 23 of top plate 11
face each other at a distance from each other. Extending portion 54
faces a portion provided with cutout portion 28 in top plate 11.
Extending portion 54 faces cutout forming surfaces 25 and 26 of top
plate 11.
[0039] A recess portion 56 formed as a partial recess in boom foot
bracket 15 is formed along extending portion 54. Recess portion 56
is recessed with respect to mount surface 59. In the state shown in
FIG. 4 where top plate 11 is mounted on mount surface 59, recess
portion 56 is formed between extending portion 54 and side surface
23 of top plate 11 that faces extending portion 54. Recess portion
56 is formed between extending portion 54 and cutout forming
surfaces 25 and 26 of top plate 11.
[0040] A groove preparation surface 57 is formed to be continuous
with recess portion 56. Groove preparation surface 57 is inclined
with respect to mount surface 59. Groove preparation surface 57 is
formed forward of recess portion 56. An edge portion 58 forms a
boundary between groove preparation surface 57 and mount surface
59. Edge portion 58 extends in the front-rear direction.
[0041] Groove preparation surface 57 is formed at a portion that
faces back surface 22 of top plate 11 in the state where top plate
11 is mounted on mount surface 59. Groove preparation surface 57
faces back surface 22 of top plate 11 and is formed in non-parallel
with back surface 22. A groove is formed between groove preparation
surface 57 and back surface 22. The groove width between groove
preparation surface 57 and back surface 22 increases gradually with
increasing distance from edge portion 58.
[0042] Due to formation of groove preparation surface 57, boom foot
bracket 15 has a portion formed to be recessed with respect to
mount surface 59. At the foremost portion of this recessed shape, a
facing surface 60 that faces side surface 32 of left side plate 12
is formed. Facing surface 60 is formed in non-parallel with side
surface 32 of left side plate 12. A groove is formed between facing
surface 60 and side surface 32. The groove width between facing
surface 60 and side surface 32 in the thickness direction of left
side plate 12 increases gradually toward surface 31 of left side
plate 12.
[0043] FIG. 7 is a plan view of region IV in FIG. 2. FIG. 7 shows a
diagram of top plate 11 and boom foot bracket 15 as seen from the
direction perpendicular to surface 21 of top plate 11. The up-down
direction in FIG. 7 corresponds to the above-described right-left
direction while the right-left direction in FIG. 7 corresponds to
the above-described front-rear direction.
[0044] As shown in FIG. 7, extending portion 54 has a facing
surface 61 that faces side surface 23 of top plate 11, more
specifically, that faces cutout forming surfaces 25 and 26. Facing
surface 61 extends along side surface 23 of top plate 11 at a
distance from top plate 11. Cutout portion 28 of top plate 11 is
formed in the longitudinal direction of box-shaped structure body
19 so as to extend from end face 24 of top plate 11 beyond leading
end 55 of extending portion 54. The length of cutout portion 28
formed in top plate 11 is greater in the front-rear direction than
the length of extending portion 54. Leading end 55 of extending
portion 54 faces cutout forming surface 26.
[0045] Cutout forming surface 25 defining a part of the boundary of
cutout portion 28 and edge portion 58 are continuous with each
other when seen from the direction perpendicular to surface 21 of
top plate 11. Cutout forming surface 25 and edge portion 58 are
flush with each other as seen in the thickness direction of top
plate 11. Cutout forming surface 25 and edge portion 58 extend
along a straight line in the front-rear direction in a top view
shown in FIG. 7.
[0046] Left side plate 12 has surface 31 shown in FIG. 4 and a back
surface 33 on the opposite side of surface 31. When seen from the
direction perpendicular to surface 21 of top plate 11, edge portion
58 and back surface 33 of left side plate 12 may be arranged in
parallel with each other. In the right-left direction, edge portion
58 may be provided between surface 31 and back surface 33 of left
side plate 12.
[0047] FIG. 8 is a side view of region IV in FIG. 2. FIG. 8 shows a
diagram of top plate 11 and boom foot bracket 15 as seen in the
direction indicated by an arrow VIII in FIG. 7. In addition, FIG. 7
shows a diagram of top plate 11 and boom foot bracket 15 as seen in
the direction indicated by an arrow VII in FIG. 8. The up-down
direction in FIG. 8 corresponds to the above-described up-down
direction while the right-left direction in FIG. 8 corresponds to
the above-described front-rear direction.
[0048] In a side view shown in FIG. 8, extending portion 54 of boom
foot bracket 15 covers a part of side surface 23 of top plate 11,
more specifically, a part of each of cutout forming surfaces 25 and
26. Cutout portion 28 is formed in a portion of side surface 23 of
top plate 11 that faces extending portion 54. When top plate 11 and
boom foot bracket 15 are seen in the right-left direction,
extending portion 54 partially overlaps with cutout forming
surfaces 25 and 26. When seen in the direction perpendicular to
surface 31 of left side plate 12, or seen in the thickness
direction of left side plate 12, a part of extending portion 54
overlaps with a part of side surface 23 of top plate 11. Extending
portion 54 has a portion that faces side surface 23 of top plate
11.
[0049] FIG. 9 is a perspective view showing the state where top
plate 11 and boom foot bracket 15 are welded to each other. FIG. 10
is a perspective view showing the state where top plate 11 and boom
foot bracket 15 are welded to each other, as seen at a different
angle.
[0050] The first groove is formed between facing surface 52 of boom
foot bracket 15 and end face 24 of top plate 11. The second groove
is formed between facing surface 61 of extending portion 54 in boom
foot bracket 15 and side surface 23 of top plate 11, more
specifically, cutout forming surfaces 25 and 26. The third groove
is formed between groove preparation surface 57 of boom foot
bracket 15 and back surface 22 of top plate 11.
[0051] The first groove, the second groove and the third groove
form a weld portion between top plate 11 and boom foot bracket 15.
End face 24 of top plate 11 forms the first groove. Recess portion
56 is formed in the bottom surface of the second groove. Edge
portion 58 of groove preparation surface 57 forms a bottom portion
of the third groove. FIGS. 9 and 10 each show a weld bead 101
formed by welding top plate 11 and boom foot bracket 15 along the
first groove, the second groove and the third groove.
[0052] The first groove is continuous with the second groove. The
second groove is continuous with the third groove. Top plate 11 and
boom foot bracket 15 can be welded in a series of the first groove,
the second groove and the third groove in this order. The first
groove is welded in the state where the opening of the first groove
is directed upward. When welding reaches the terminal end of the
first groove, top plate 11 and boom foot bracket 15 are integrally
rotated in the direction indicated by an arrow shown in FIG. 10.
Then, the opening of the second groove is directed upward, in which
state the second groove is welded. When welding reaches the
terminal end of the second groove, top plate 11 and boom foot
bracket 15 are further rotated in the direction indicated by the
arrow shown in FIG. 10. Then, the opening of the third groove is
directed upward, in which state the third groove is welded. In this
way, the first, second and third grooves are sequentially welded,
so that top plate 11 and boom foot bracket 15 are joined to each
other.
[0053] By attaching top plate 11 and boom foot bracket 15 to a
positioner of a welding robot, top plate 11 and boom foot bracket
15 can be automatically integrally rotated. When the first groove
is welded, top plate 11 is disposed so as to extend approximately
in the horizontal direction. When the second groove is welded, top
plate 11 is disposed so as to be inclined with respect to the
horizontal direction and the vertical direction. When the third
groove is welded, top plate 11 is disposed approximately in the
vertical direction.
[0054] The fourth groove is formed between side surface 32 of left
side plate 12 and facing surface 60 of boom foot bracket 15. The
fifth weld portion that is welded by fillet welding is formed
between back surface 22 of top plate 11 and surface 31 of left side
plate 12. Weld bead 111 shown in FIG. 3 represents a weld bead
obtained by welding back surface 22 of top plate 11 and surface 31
of left side plate 12 by fillet welding.
[0055] When welding reaches the terminal end of the third groove,
then, the fourth groove or the fifth weld portion is welded. The
first, second and third grooves are welded repeatedly several times
in order to sufficiently ensure the throat depth. In a series of
welding operations, until welding of the fourth groove is
completed, welding of the third groove may be followed by welding
of the fourth groove. Then, welding of the third groove may be
followed by welding of the fifth weld portion. In this way, welding
of the first to third grooves is followed by continuous welding of
the fourth groove or the fifth weld portion, with the result that
boom foot bracket 15 and left side plate 12 are joined to each
other while top plate 11 and left side plate 12 are joined to each
other.
[0056] The characteristic configurations of the present embodiment
will be set forth below though a part of the configurations may be
repeatedly described. Boom 5 in the present embodiment corresponds
to boom 5 used in hydraulic excavator 100 shown in FIG. 1 and
includes top plate 11, left side plate 12, right side plate 13, and
bottom plate 14, as shown in FIGS. 2 and 3. Left side plate 12 is
joined to top plate 11. Right side plate 13 is joined to the top
plate and faces left side plate 12 at a distance from left side
plate 12. Bottom plate 14 is joined to left side plate 12 and right
side plate 13, and faces top plate 11 at a distance from top plate
11. Top plate 11, left side plate 12, right side plate 13, and
bottom plate 14 are joined to one another to form box-shaped
structure body 19 shown in FIG. 3. Top plate 11, left side plate
12, right side plate 13, and bottom plate 14 in the embodiment
correspond to the first plate material, the second plate material,
the third plate material, and the fourth plate material,
respectively.
[0057] Boom 5 further includes boom foot bracket 15, as shown in
FIG. 2. Boom foot bracket 15 is joined to each of top plate 11,
left side plate 12, right side plate 13, and bottom plate 14 at the
end of box-shaped structure body 19 shown in FIG. 3 in its
longitudinal direction. As shown in FIGS. 4 and 6 to 8, boom foot
bracket 15 has extending portion 54. Extending portion 54 extends
in the longitudinal direction of box-shaped structure body 19.
Extending portion 54 has a portion that faces side surface 23 of
top plate 11, as shown in FIGS. 4, 7 and 8. Boom foot bracket 15 in
the embodiment corresponds to the first attachment member.
[0058] When the first groove formed of end face 24 of top plate 11
and facing surface 52 of boom foot bracket 15 is welded, molten
metal is dammed up due to existence of extending portion 54. Since
extending portion 54 is provided and extending portion 54 functions
as a dam to prevent an overflow of molten metal during the welding
operation, a sufficient throat depth can be ensured when the first
groove is welded. Thereby, the number of steps required for the
welding operation of the first groove can be reduced while the
welding quality for the first groove can be improved.
[0059] The second groove is formed of side surface 23 of top plate
11 and facing surface 61 of extending portion 54. The first groove
and the second groove are formed to communicate with each other.
Thereby, welding can be smoothly shifted from the first groove to
the second groove. Since the first groove and the second groove can
be continuously welded, the number of steps required for the
welding operation can be reduced. The first groove and the second
groove can be continuously welded using a welding robot, thereby
allowing stabilized welding, so that the welding quality can be
improved.
[0060] Also as shown in FIGS. 4, 5, 7, and 8, cutout portion 28 is
formed in the portion of top plate 11 that faces extending portion
54. The second groove is formed of: cutout forming surfaces 25 and
26 in side surface 23 of top plate 11, which form cutout portion
28; and facing surface 60 of extending portion 54. The third groove
is formed of back surface 22 of top plate 11 and groove preparation
surface 57 of boom foot bracket 15. By forming cutout portion 28 in
top plate 11, the second groove and the third groove can be formed
to communicate with each other, so that welding can be smoothly
shifted from the second groove to the third groove. Since the
second groove and the third groove can be continuously welded, the
number of steps required for the welding operation can be reduced.
The second groove and the third groove can be continuously welded
using a welding robot, which allows stabilized welding, so that the
welding quality can be improved.
[0061] Also as shown in FIGS. 4 and 8, top plate 11 has surface 21
and back surface 22 on the opposite side of surface 21. Surface 21
forms the outer surface of box-shaped structure body 19 shown in
FIG. 3. Surface 21 in the embodiment corresponds to the first
surface while back surface 22 corresponds to the first back
surface. As shown in FIGS. 6 to 8, groove preparation surface 57 is
formed in a portion of boom foot bracket 15 that faces back surface
22 of top plate 11. Together with back surface 22, groove
preparation surface 57 forms the third groove. Edge portion 58 of
groove preparation surface 57 forms the bottom portion of the third
groove. As shown in FIG. 7, cutout forming surface 25 and edge
portion 58 are continuous with each other, as seen from the
direction perpendicular to surface 21 of top plate 11.
[0062] Cutout forming surface 25 and edge portion 58 are provided
flush with each other, so that smooth shifting of welding from the
second groove to the third groove can be further more facilitated.
Since the second groove and the third groove can be continuously
welded with more reliability, the number of steps required for the
welding operation can be reduced while the welding quality can be
improved.
[0063] Also as shown in FIGS. 7 and 8, cutout portion 28 is formed
to extend from end face 24 of top plate 11 beyond leading end 55 of
extending portion 54. By defining the range in which cutout portion
28 is formed in this way, it becomes possible to avoid interference
of extending portion 54 with the nozzle at the end of a welding
machine when welding is shifted from the second groove to the third
groove. Accordingly, smooth shifting of welding from the second
groove to the third groove can be further more facilitated.
[0064] Also as shown in FIGS. 4 and 6, recess portion 56 formed as
a partial recess in the surface of boom foot bracket 15 is provided
between extending portion 54 and side surface 23 of top plate 11
that faces extending portion 54. When the first groove, the second
groove and the third groove are continuously welded, top plate 11
and boom foot bracket 15 need to be rotated during welding. By
providing recess portion 56, molten metal can be accumulated in
recess portion 56 during rotation, so that it becomes possible to
implement the configuration in which molten metal is further less
likely to overflow during the welding operation. By filling up
recess portion 56 by welding, flat weld bead 101 can be obtained
while the throat depth required for the second groove can be
ensured.
[0065] Also as shown in FIGS. 4, 6 and 8, extending portion 54 has
a bank shape formed such that the protrusion height decreases
toward leading end 55. By defining the shape of extending portion
54 in this way, it becomes possible to avoid interference of
extending portion 54 with the nozzle at the end of a welding
machine when welding is shifted from the second groove to the third
groove. Accordingly, smooth shifting of welding from the second
groove to the third groove can be further more facilitated.
[0066] In boom 5 in the present embodiment having the configuration
as described above, the weld line can be formed to extend
continuously from the first groove to the third groove, so that
continuous welding can be performed using a welding robot.
Accordingly, the number of steps required for the welding operation
can be reduced while the welding quality can be improved. The
corner portion of boom 5 at which a stress concentration is more
likely to occur is automatically continuously welded, to thereby
improve the welding quality, so that the strength of boom 5 can be
enhanced.
[0067] Preferably, boom foot bracket 15 is a cast product.
Complicatedly-shaped boom foot bracket 15 including extending
portion 54, recess portion 56, groove preparation surface 57 and
the like is integrally molded by casting using an appropriate metal
mold prepared in advance, so that this boom foot bracket 15 can
readily be molded. Thus, the number of steps required for molding
boom foot bracket 15 can be reduced while variations in shape of
the molded product can be reduced.
[0068] In the above-described embodiment, welding between top plate
11 and boom foot bracket 15 in boom 5 of work implement 4 has been
described. The present invention can be applicable also to the case
where arm 6 of work implement 4 is molded by welding. Work
implement 4 of hydraulic excavator 100 that is an object of the
present invention refers to boom 5 and arm 6.
[0069] FIG. 11 is a side view showing the schematic configuration
of arm 6 shown in FIG. 1. As shown in FIG. 11, arm 6 has a top
plate 71, a bottom plate 74, an arm cylinder attachment bracket 75,
and an arm top bracket 76. Arm cylinder attachment bracket 75 is
joined at one end of arm 6 in its longitudinal direction to top
plate 71 and bottom plate 74. Arm top bracket 76 is joined at the
other end of arm 6 in its longitudinal direction to top plate 71
and bottom plate 74. Arm cylinder attachment bracket 75 forms the
rear end portion of arm 6 while arm top bracket 76 forms the front
end portion of arm 6. Arm top bracket 76 is a cast product molded
by casting.
[0070] A boom connection hole 77 is formed at the position in the
vicinity of arm cylinder attachment bracket 75 in the longitudinal
direction of arm 6. Arm attachment bracket 16 shown in FIG. 3 is
coupled to boom connection hole 77.
[0071] The same configurations as those of boom foot bracket 15 and
top plate 11 described above are applied to the welding portion
between arm top bracket 76 and top plate 71, so that the number of
steps required for the welding operation can be reduced while the
welding quality can be improved.
[0072] It should be understood that the embodiments disclosed
herein are illustrative and non-restrictive in every respect. The
scope of the present invention is defined by the terms of the
claims, rather than the description above, and is intended to
include any modifications within the meaning and scope equivalent
to the terms of the claims.
REFERENCE SIGNS LIST
[0073] 4 work implement, 5 boom, 6 arm, 11 top plate, 12 left side
plate, 13 right side plate, 14 bottom plate, 15 boom foot bracket,
19 box-shaped structure body, 21, 31 surface, 22, 33 back surface,
23, 32 side surface, 24 end face, 25, 26 cutout forming surface, 28
cutout portion, 51 rear wall portion, 52, 60, 61 facing surface, 54
extending portion, 55 leading end, 56 recess portion, 57 groove
preparation surface, 58 edge portion, 59 mount surface, 76 arm top
bracket, 100 hydraulic excavator, 101, 111, 112, 113, 114 weld
bead.
* * * * *